1. Field of the Invention
The present invention relates to an accumulator used in a refrigerant cycle for an automobile air conditioner or the like.
2. Description of the Related Art
One example of a conventional accumulator is shown in FIG. 15. The accumulator includes a U-shaped suction pipe 204 provided in a tank 201 for separating refrigerant evaporated in an evaporator (not shown) into gaseous refrigerant and liquid refrigerant. A defroster 220 in the shape or an umbrella or a reversed-cup is also provided in the tank 210 for an effective separation of gaseous refrigerant and liquid refrigerant, even in a case where the accumulator vibrates or swings. Also provided in the tank 201 is a dryer unit 202 to dehydrate the refrigerant. The dryer unit 202 has a specific configuration so as to avoid the suction pipe 204. At the bottom portion of the tank 201, an oil returning opening (not shown) is provided in order to return lubricant oil to a compressor (not shown). A filter having a specific structure is provided in the suction pipe 204 at the bottom portion thereof.
As explained above, a conventional accumulator is composed of many parts including the suction pipe 204, the defroster 220, the dryer unit 202, and the filter. Further, each of these parts has a complicated and peculiar shape and/or structure, which causes an increase in a manufacturing cost of the accumulator.
The conventional accumulator has other drawbacks that a refrigerant pressure loss in the accumulator is relatively large because the refrigerant passes through the U-shaped suction pipe 204 provided in the tank 201, and the upper and opening of the suction pipe 204 is covered by a defroster 220. The filter mounted in the suction pipe 204 also increases the loss of refrigerant pressure.
In this kind of refrigerant cycle, a certain amount of lubricant oil for lubricating a compressor (hereinafter referred to as "lubricant oil") is added to the refrigerant. In the accumulator constituting the refrigerant cycle, the refrigerant containing the lubricant oil is separated into gaseous refrigerant, liquid refrigerant and lubricant oil. Then, the gaseous refrigerant and the lubricant oil are introduced into a compressor from the accumulator. At the same time, in the accumulator, the refrigerant is dehydrated by the dryer unit 202 disposed in the tank 201.
Thus, an accumulator has various functions including a refrigerant-separate-function for separating refrigerant into gaseous refrigerant and liquid refrigerant, a liquid-store-function for storing liquid refrigerant, a oil-supply-function for supplying a certain amount of lubricant oil to a compressor, and a dehydrate-function for removing water contained in the refrigerant cycle.
In the tank 201, liquid refrigerant and lubricant oil are accumulated at the bottom portion of the tank 201 in a separated manner such that a liquid refrigerant layer stays on a lubricant oil layer because the former is lighter than the latter in specific gravity. Especially, in a case where a large amount of liquid refrigerant is accumulated in the tank 201, the lubricant oil cannot be supplied to the compressor until the liquid refrigerant forming the lower layer is completely discharged because the oil returning opening (not shown) is formed at the bottom portion of the tank 201. As a result, the aforementioned oil-supply-function of the accumulator cannot be performed.
Furthermore, immediately after the refrigeration cycle begins to operate, the liquid refrigerant may be supplied to a compressor through the oil returning opening, which may cause trouble of the compressor.